Simulation and Ac Electrical Properties of Disordered Materials. Application to Semiconductors and Clays

The frequency dependence of the complex electrical impedance ( Z* ) and modulus ( M* ) of two types of semiconducting materials, is studied. These are Cu 5 In 9 Se 16 (CIS), an ordered defect compound of the I-III-VI 2 family and a novel bentonite clay system which is insulator at room temperature and semiconductor above 400 °C. The experimental data of Z* and M* are analysed using three derivative methods that take into account the effect of the grains and grain boundaries. The impedance data confirm the non-Debye behavior in these systems. Some important parameters related to the grains " g " and grain boundaries " gb " like electrical resistances R g and R gb , capacitances C g and C gb , relaxation times τ g and τ gb and activation energies for the conduction and relaxation mechanisms are estimated